OS030. Hypertension and labor duration: Does it take longer?

Hypertensive disease in pregnancy carries higher maternal and fetal morbidity and mortality and often requires labor induction to minimize risk. It was previously taught that preeclampsia was associated with a more rapid progression through all stages of labor, while there is a paucity of data in other hypertensive categories. One investigation in preeclamptic women demonstrated that labor progress was prolonged with increased risk for cesarean delivery.

To study labor progression in induced nulliparas at term with hypertensive diseases in pregnancy.

Retrospective cohort study using data from the Consortium on Safe Labor; a multicenter project that abstracted labor and delivery information from electronic medical records in 19 hospitals across the US. A total of 32,276 women with singleton term gestation, induced labor, and vertex presentation were studied. Hypertensive women were grouped into 4 separate categories: chronic hypertension (cHTN), gestational hypertension (gHTN), preeclampsia (PreE) and superimposed preeclampsia (SIPreE) and compared to controls (no hypertensive disorder). For the first stage of labor, Interval-censored regression analysis was used to estimate median and 95th% duration of labor, centimeter by centimeter and from 4-10cm.

Significant differences were noted in demographics between each group and controls including age, race, labor admission body mass index, gestational age at delivery, comorbidities, and admission cervical dilation (P<0.01 for all comparisons to the control group). As noted in the table, women with cHTN and SIPreE had a longer first stage of labor, gHTN had a shorter first stage of labor, and labor length was similar in PreE compared to controls. Second stage of labor was longer (5-41min) with epidural and varied among groups; however, the clinical significance is limited. 95th% for progression from 4-10cm in cHTN, SIPreE and gHTN were 27.4, 28.2 and 16.5h respectively (controls 20.1h) ().

In nulliparas induced at term with hypertensive disease, labor progression in the first and second stage varies from controls. gHTN women have the shortest first stage of labor while PreE gravidas have labor patterns similar to controls. As cHTN and SIPreE women have a longer first stage, allowing labor to continue for a longer period in these gravidas may contribute to a reduced rate of cesarean delivery in the US, but will require further investigation.